Hydraulic transmission



Aug. 30, 1949;

w. FERRIS HYDRAULIC TRANSMISSION s Sheets-Sheet 1 Filed Aug. 28, 1944 coho! OEhOuJu Z a 2. 2. 383mm umammumm 9. t N\ I J, 2: mm mo. w 0.@ mm mm B. m Jw /AF J H H.@ I w 1 no. 533: Ill No. 53 Q :3 S o i no. o E. m, f Am r r f K \JQCb-UIUKEQ 55 6 Ema.

INVENTOR WALTER FERRIS ATTORNEY Aug. 30, 1949. FER I' 2,480,403

HYDRAULIC TRANSMISSION Filed Aug. 28, 1944 v a Sheets-Sheet 2 FIG. 7 e5 e1 95 a 97 27 2 94 3/ v uoe- 93 FIG. 2

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ATTORNEY Aug. 30, 1949. w. FERRIS 2,480,403

HYDRAULIC TRANSMISSION Filed Aug. 28, 1944 r s Sheefs-Shet 3 .us no i\\ 6 |o9 FIG. 9 I20 I v I we ".05

us Q I FIG. '0 67 68 &\ II V Y 64 I! x Fue. Il I -63 5 v & I

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sir- 2| 25 26 24 22 l 1 27 INVENTOR WALT-ER FERRIS ATTORNEY Patented Aug. 3Q, 1949 Walter Ferris, Milwaukee, Wis., asslgnor to The Ollgear Company, Milwaukee, Wis., a corporation of Wisconsin Application August 28, 1944,-Serial No. 551,578

This invention relates to hydraulic transmissions of the type inwhich the speed of the hydraulic motor is controlled by throttling the liquid and it has as an object to provide such a transmission including means for maintaining the for maintaining the adjustment of the difierential mechanism unchanged from the end of one feeding phase of a cyclethrough the intervening rapid traverse phase to the beginning of the next feeding phase. I

Other objects and advantages will be apparent from the description hereinafter given of a hydraulic transmission in which the invention is embodied.

The invention is exemplified by the transmission shown schematically in the accompanying drawings inwhich the views are as follows:

Fig. 1 is a. hydraulic circuit diagram showing the relation between the several parts of the transmission.

Figs. 2, 3, 4, 5 and 6 are views showing the several operative positions of the control valve shown in Fig. 1.

Fig. 7 is a view illustrating the positions of the cams for shifting the control valve from one to another of its several positions.

Fig. 8 is a central longitudinal section through the pressure reducing valve shown in Fig. 1.

Fig. 9 is a section through the drum which carries the cams illustrated schematically in Fig. '7, the view being taken on a line 9-9 of ,Fig. 1.

Fig. 10 is a view taken on a line ll0 of Figs. 1 and 11.

Fig. 11 is in part a side view and in part a section taken on the line ||-.-ll of Fi 10.

The transmission may have a rotary motor but, for the purpose of illustration, it has been shown as having a reciprocating motor consisting primarily of a stationary cylinder I and a piston 2 fitted in cylinder I and connected by a rod 3 to a crosshead 4 or other movable element. Piston 2 is adapted to be moved in one direction or the other at rapid traverse rates and in one direction at feed rates by liquid supplied freely to one end or theother of cylinder I from a suitable source such as a pump driven by an electric motor 6.

When motor l--2 is operating at rapid traverse chamber In formed therein.

20 Claims. CL- -52) rates, the outflow therefrom is substantially unrestricted but. when it is operating at feed rate, the outflow therefrom and consequently the speed thereof is controlled by a throttle valve 1 which is fitted in a casing 8 and controls communication between an intake chamber 9 and a discharge A plurality of tapered grooves ll formed in the periphery of valve 7 coact with the wall of casing Hi to form a plurality of orifices through which liquid delivered from cylinder I to chamber 9 flows to discharge chamber Hi. Valve is held in adjusted positions and adapted to be moved toward the right by mechanism to be presently described and it is constantly urged toward the left by a spring I2 arranged within a spring chamber 13 formed in the right end of casing 8. Moving valve 5 toward the left or toward the right increases or decreases the orlflce area or the efiective areas of grooves H.

The rate of flow through a throttle valve is substantially proportional to the drop in pressure thereacross subject to variations due to changes in the viscosity of the liquid, partial choking of the throttle by sediment in the working liquid etc. In order that the flow through grooves H and consequently the rate at which liquid is dis charged from cylinder 6 may be substantially constant when valve l isin any given position, discharge chamber to is connected to drain, as by being connected to a reservoir it by a channel which is also connected to spring chamber 63, and intake chamber a isconnected by a channel it to a pressure reducing valve H which reduces the pressure of the incoming liquid to a constant low value so that the drop in pressure across the orifices remains substantially constant during the large fluctuations in working pressure which frequently occur.

Reducing valveill not only maintains a, con stant pressure in inlet chamber 9 so that the flow through grooves H is constant when valve l is stationary, but it also reduces the pressure to a low value, such as 30 p. s. 1., so thatgrooves H may be made large enough to prevent them from becoming clogged with small particles ofsolid matter which accumulatein the motive liquid.

As shown in Fig. .8, reducing valve I! has a valve member l8 fitted in a casing is and urged against the right end thereof by spring 20 ar- Channel I6 is connected to casing 19 in communication with a cannelure 25 formed in valve member iii in communication with an annular port 26 to which liquid discharged from the lower end of cylinder I is directed through a channel 21. Cannelure 25 also communicates with a channe1 28 which extends therefrom through the right end of valve member I 8 and'has a choke29 arranged therein.

The arrangement is such that liquid discharged from motor |2 enters port 26 through channel 21 and then flows through cannelure 25 and channel iii to throttle 18 which resists the flow of liquid therethrough and thereby causes pressure to rise. This pressure extends from cannelure 25 through channel 28 to the right end of easing l9 and moves valve member l8 toward the left against the resistance of spring 20, there-'- by reducing the opening between the adjacent edges of cannelure 25 and port 26 which edges form an orifice to throttle the flow and cause a drop in pressure thereacross. Valve member IE will continue to move toward the left until the pressure in cannelure 25 and in the right end of casing I9 is such a low value, for example 30 p. s. 1., that the force exerted by the liquid upon the right end of valve member I8 is equal to the resistance of spring 20.

V men the pressure of the incoming liquid increases, the flow from port 26 to cannelure 25 tends to increase but throttle 1-8 resists an increase in the flow therethrough and thereby causes a momentary increase in the pressure in cannelure 25 and in the right end of easing i9. This momentary increase in pressure moves valve member l8 toward the left until the pressure in the right end of easing l9 and at the inlet of throttle 1 is again proportional to the resistance of spring 20.

When the pressure of the incoming liquid decreases, the flow from port 26 to cannelure 25 decreases and thereby causes a drop in the pressure acting upon the right end of valve member l8 which permits spring 20 to move valve member [8 toward the right to increase the opening between the adjacent edges of cannelure 25 and port 26 until the pressure acting upon the right end of valve member is again proportional to the resistance of spring 20. Reducing valve I 1 thus automatically adjusts itself to maintain a constant pressure at the inlet of throttle 1, and choke 29 slows down the movement of valve member I8 to prevent it from hunting.

Passing the outflow from a hydraulic motor through a throttle and maintaining a substantially constant pressure at the inlet of the throttle keeps the speed of the motor near enough to constant for some purposes but for other purposes the motor speed should be either constant or exactly proportional to a reference speed.

In order that the motor speed may be maintained proportional to a reference speed which may be constant, the present invention provides a differential 35 which has one leg driven at a speed proportional to the motor speed, a second leg driven at a speed proportional to a reference speed and its third leg adapted to adjust throttle valve 1 in response to a variation in the relative speeds of the first and second legs. Throttle valve 1 is adjusted to approximately establish a desired motor speed and then a variation in the motor speed relative to the reference speed will cause differential 35 to further adjust 4: In order that the motor speed may be varied relative to the reference speed, the second leg of differential 35 is driven through a control transmission 36 which may be adjusted-to vary the speed of differential 35 relative to the reference speed. Transmission 36 is preferably of the friction type and. since such transmissions are well known, ithas been shown'schematically'and only as much thereof illustrated as is necessary to an explanation of its functions.

As shown, transmission 36 includes a driven disk 31 which is suitably mounted for rotation, a cylindrical friction roller 38 which is journaled in stationary bearings 39 and 48 and provided with a shaft 4| for transmitting motion to differential35, and a pair of transfer balls 42 and 43 arranged in a carriage 44 and interposed between disk 31 and roller 38. Disk 31 is urged by spring means, not shown, toward roller 38 to pinch balls 42 and 43 therebetweenso that they can transmit motion from one to the other.

Carriage 44 is constantly urged toward the right by a spring 45 arranged between bearing 40 and an arm 46 fixed upon a rod 41 which is connected to or formed integral with carriage 44. Movement of carriage 44 toward the right is limited by the right end of rod 41 engaging a piston 48 which is fitted in a stationary cylinder 49 and normally held by spring 45 against an adjusting screw 50 threaded through the end of cylinder 49. Piston 48, when operated by liquid supplied to cylinder 49, willmove carriage 44 toward the left into engagement with an adjusting screw 5| carried by bearing 39.

Disk 31 is driven at a reference speed to which the speed of the hydraulic motor is to be maintained proportional. If the motor speed is to be constant when the motor is operating at a feed rate, disk 31 may be driven by a synchronous motor but, since during the time the hydraulic motor is operating at a feed rate the speed of motor 6 remains substantially constant due to the fact that pump 5 is operating at short stroke and at a substantially constant pressure during that time, disk 31 has been shown as being driven by electric motor 6 through a drive 52 which has been indicated simply by a dotted line as any suitable drive will sufllce.

Differential 35 has been shown schematically as it is of ordinary construction and an illustration thereof in detail is deemed unnecessary. One leg of differential 35 includes a housing 56 which is journaled in stationary bearings 51 and 58 and has a gear 59 fixed thereon and driven at a speed proportional to the speed of motor [-2 through a drive to be presently described. A second leg of differential 35 includes a shaft 60 which extends through the left end of housing 56 and is driven from shaft 4| of transmission 36 through a drive 6| which has been indicated by a. dotted line as any suitable drive will suflice.

The third leg of differential 35 includes a shaft 62 which extends through the right end of houstor speed.

ing 56 and has fixed upon its outer end a cam 63 (Figs. 10 and 11) having a helical groove or cam slot 64 formed in its periphery. Cam 63 is rotatable within a sleeve 65 having a cam follower 66 fixed thereto and extending into cam slot 64. Sleeve 65 is connected by two diametrically opposed trunnions 61 to the forked upper end of a lever 68 which isengaged intermediate its ends -by throttle valve 1 and has its lower end slotted and pivoted upon a pin 69 fixed to rod 41 as shown in Fig. 1.

The arrangement is such that a variation in upon shaft 1 I valve I toward the right to decrease the effectivev areas of grooves Ii or it will permit spring I2 to move throttle valve I toward the left to increase the effective areas of grooves i I. I

Gear 59 on differential housing 66 has been shown in mesh with a gear III which is journaled upon a stationary shaft II and adapted to be fixed for rotation with a gear I2 also journaled Gear 12 meshes with a gear 13 which is rotatable upon a stationary axis and has a sheave or cable drum 14 fixed thereto. Gear 13 is adapted to be rotated in one direction by a torsion spring 15 and it is adapted to be rotated in the opposite direction by motor l-2 through a cable 16 which has one end connected to crosshead 4 and its other end portion wound I upon and fixed to drum 14, cable 16 being passed over suitable deflector sheaves 11 if necessary.

The arrangement is such that, when piston 2 is advanced on a working stroke, crosshead 4 will unwind cable 16 from drum 14 which will cause gears 13, 12, i and 59 to rotate differential housing 56 in one direction at a speed proportional to the speed of piston 2 and will also cause sufficient energy to be stored in spring 15 to drive these gears in the opposite direction and maintain a tension in'cable 16. When piston 2 is retracted, spring 15 will rotate gear 13 and drum 14 in the opposite direction to wind cable 16 upon drum I4, and cable 16 will maintain the speed of gear 13 proportional to the speed of piston 2.

In the transmission shown, motor l2 is adapted to operate at rapid traverse speed in opposite directions and to operate in one direction at feed rate which may be varied from zero to a predetermined maximum. As previously explained, throttle valve 1 is adjusted to cause motor !-2 to operate at a predetermined feed rate and then any variation in that rate will cause differential 35 to adjust throttle valve '5 to correct such variation in speed.

In order that differential 55 may operate to maintain a feed rate constant or proportional to a reference speed, drives 52 and 68 are so proportioned that, with carriage 44 against fast feed adjusting screw 58, shaft 50 will be driven at a speed proportional to the speed at which difierential housing 55 is driven when 'motor l-2 is operating at a predetermined maximum feeding rate. Then by moving carriage 6 3 toward the right, the speed of motor l-2 will be reduced until further movement of carriage 46 is pre- I R. P. M. at the minimum feed rate of one half inch per minute, that the maximum feed rate is 18 inches per minute and that the rapid traverserate is 18 feet per minute, the speed of differential housing 56 will be 144 R. P. M. when motor 1-2 is operating at maximum feed rate and, if differential housing 56 were driven during rapid traverse of motor l2, its

speed would'be 12 times its speed during maximum feed.

The speeds of shaft 60 and differential housing 56 are proportional to each other at all feed rates.

but changing the speed of motor l-2 from feed to rapid traverse does not cause a corresponding change in the speed of shaft 60. Therefore, if

tate without rotating gear Ill during rapid traverse.

As shown, gear "is adapted to be pressed against gear 12 by a piston 18 fitted in a stationary cylinder 19 to which pressure liquid is supplied through channel 21 only during feed. Movement of gear 12 along shaft II" is resisted by a spring 81] arranged around shaft II between a bearing 8! and a collar 82 which is slideable upon shaft H and has a suitable notch, formed therein to receive a pin 83 fixed in shaft H.

The arrangement is such that, when pressure liquid is supplied to cylinder 19, piston 18 will press gear ill against gear 12 and move both gears along shaft II against the resistance of spring 80 until further movement of piston 18 1s arrested by its head engaging the end of cylinder 19. Gear 12 is thus pressed against gear Ill by a force proportional to the resistance of spring 86 and the friction between the adjacent hubs of gears 12 and 10 enables gear 12 to drive gear Iii. When cylinder 19 isconnected to drain, spring 8t will move collar 82 and gears 12 and Ill along shaft H until collar 82 engages pin 83 and then there is no force to press gears 12 and ill together and gear 12 may rotate without rotating gear it so that differential housing 56 is not driven by ear 10 during rapid traverse of motor l--2.

- Due to frequent alternation between rapid traverse and feeding operations in such machines as machine tools to which-the present device is applicable, it is essential that the difierential corrections in the position of valve i made during the feeding phase of a cycle be maintained during the succeeding rapid traverse phase while clutch ill-12 is'disengaged. The duration of the feedin phase in many set-ups is quite short, and if valve 7 were permitted to revert each time to its manually adjusted position, the entire feeding period might elapse before the differential correction was completed and the feed rate corrected.

In order to retain throttle valve i in its adjusted position during rapid traverse, a brake at is 60 slideably splined upon shaft 62 between bearing 57 and cam 63. Brake 84 is pressed against bearing 51 by spring l2 which exerts sufi'icient force to enable brake 84 to hold shaft 62stationary during rapid traverse but not enough force to pre- 65 vent shaft 62 from-readily rotating in response to a variation in the relative speeds of shaft 60 and differential housing 56 during feed.

I Operation of motor l--2 is controlled primarily by valve means which isadjustable to direct liquid .70 from pump 5 to one end or the other of cylinder I, to direct the outflow from cylinder l topressure reducing valve T1, to direct pressure liquid to cylinders 49 and i9 and to cut off flow .toboth ends of cylinder I simultaneously. The valve 76 means may assume various forms but'it has been shown as including a control valve 86 which is fitted in a casing 86 and controls communication between six annular grooves or ports 81, 88, 88, 00, SI and 92 formed in the wall of casing 86. Valve 85 has a passage 93 extendin therethrough from the right end thereof and opening into casing 86 near the left end thereof so that it is always in communication with port 81 to which drain channel 24 is connected. A chamber 94' of substantially the same diameter as the ports is formed in the right end of casing 86 to permit liquid to flow from certain ports through passage 93 to drain channel 24.

Port 88 is connected by a channel 95 to the upper end of cylinder I, port 80 is connected by a channel 96 to the outlet of pump 5 and port 80 is connected to the lower end of cylinder I by a channel 91 having a check valve 08 and a resistance valve 99 connected therein in paralla with each other and opening in opposite directions. Check valve 98 permits liquid to flow freely into cylinder I but prevents discharge of liquid therefrom except through resistance valve 99 which offers suiiicient resistance to the discharge of liquid to prevent piston 2 from moving when the transmission is idle. Port 9| has channel 21 connected thereto and port 92 is connected by a channel I to cylinder 49.

Valve 85 has a stem IOI fixed to its left end and extending through a block I 02 to which it is releasably connected by a detent I03. Block I02 is slidable upon a stationary rod I04 and urged toward the right by a sprin I05 so that valve 85 is constantly urged toward the right when stem IN is connected to block I02 by detent I03.

When valve 85 is in the position shown in Figs. 1 and 2,motor I2 is idle and a cam roller I06 journaled in block I02 is in engagement with a neutral cam I07 carried by a cam drum I08 which is driven through a gear reducer I09 from cable drum 14 so that operation of motor I2 causes cam drum I08 to rotate through an angular distance exactly proportional to the linear distance through which crosshead 4 is moved. Total angular travel of cam drum I08 must not exceed one full revolution.

Cam drum I08 also has arranged thereon a rapid traverse cam IIO, a fast feed cam III and a slow feed cam II2 which cam roller I06 is adapted to engage in succession as indicated in Fig. '7. When roller I06 is in engagement with cam I I0, valve 85 is in the position shown in Fig. 3 and piston 2 will be advanced at rapid traverse r'ate. During rotation of drum I 08, roller I 06 will move into engagement with cams I II and H2 successively and spring I05 will move valve 85 successively into the positions shown in Figs.

4 and 5 which will cause piston 2 to be advanced first at a fast feed rate and then at a slow feed rate. During continued rotation of cam drum I08, roller I06 will move out of engagement with the cams and spring I05 will move valve 85 to the position shown in Fig. 6 which will cause piston 2 to be retracted at rapid traverse rate.

Cams I01, IIO, III and H2 are circular segments and are fitted into under cut slots I I3 and H4 which are formed in the peripheral wall of drum I08 as shown in Figs. '7 and 9. Each cam is clamped in position by screws II5 extending therethrough and threaded into nuts 6' which are arranged in the under cut portion of the slot in which the cam is fitted. The length of each of cams IIO, III and H2 is approximately proportional to the required movement of crosshead 4 which that cam is to control. For example, the

length of rapid traverse cam II I is proportional to the distance through which crosshead 8 moves during rapid traverse forward. Minor adjustments in rapid traverse stroke'and feed strokes may be made by shifting the cam segments in grooves II3, each cam segment being made to overlap the adjacent segment for that purpose as indicated in Fig. 7.

Motor I2 may be operated at substantially its full stroke but it is ordinarily operated at a shorter stroke and, in order to select the range in which piston 2 reciprocates, cam drum I08 may be rotated relatively to the output shaft of gear reducer I09. As shown in Fig. 9, the output shaft of gear reducer I 09 has a socket II'I rigidly secured thereto and cam drum I06 is fitted in socket Ill and provided at .its lower end with an internal annular flange II8 which is engaged by a plate II9. A plurality of bolts I20 extend through plate H9 and are threaded into socket II! to clamp cam drum I08 firmly to socket Ill. The arrangement is such that, after the cams have been clamped in position upon drum I 08, bolts I20 may be loosened and drum I08 rotated relative to socket Ill and then clamped in a desired position by tightening bolts I20.

If motor I2 were operated by liquid supplied thereto by a constant displacement pump, the entire output of the pump would be utilized during rapid traverse of motor I2 and there would be no loss of power butv when motor I2 was operated at a feed rate, only a small part of the liquid discharged by the pump would be utilized in driving the motor and the balance would be exhausted through a relief valve which would waste considerable power and cause the liquid to become heated.

If motor I2 were operated by liquid supplied thereto from a pump of the well known pressure responsive type which delivers liquid at a predetermined maximum rate until pump pressure reaches a predetermined maximum and then it reduces its displacement until it is delivering just enough liquid to maintain that maximum pressure constant, there would be no appreciable loss of power or heating of the liquid but it would be necessary for the pump to operate at a displacement near zero when motor I2 was operating a minimum feed rate and such pumps are inclined to hunt when operating at a displacement near zero.

In order to avoid hunting of the pump and also avoid loss of a substantial amount of power. pump 5 is provided with a control which enables it to deliver at a predetermined maximum rate until pressure reaches a predetermined maximum and to then reduce its delivery to a minimum rate which is great enough to operate motor I2 at fast feed rate. When motor I-2 is operating at slow feed rate, the liquid discharged by the pump in excess of motor requirements is exhausted through a relief valve but the rate at which liquid is exhausted-through the relief valve is so small relative to the maximum rate of pump delivery that the loss of power and the resultant heating of the liquid are practically negligible.

For example, the displacement varying mechanism of pump 5 may include two pistons I2I and I22 arranged, respectively, in two cylinders I23 and I24 which are fixed to opposite sides of the pump casing. A spring I25 arranged between piston I2I and the end of cylinder I23 urges pistons I2I and I22 toward the left to increase idly upon shaft 'II.

pump displacement and it tends to hold'piston I22 against an adjusting screw I28 which is,

'threaded through the end of cylinder I24 and determines the maximum displacement of the pump. Piston I22 is adaptedto be moved toward the right to decrease pump displacement by liquid supplied to the outer endof cylinder I 24 through a channel I2'I from channel 96. Themovement of piston I22 toward'the right is limited by piston I2I engaging an adjusting screw I28 threaded through the end of cylinder I23 and determining the minimum pump displacement which is kept great enough to enable pump 5 to deliver liquid at a rate sumcient to operate motor I2 at a maximum feed rate. When motor I2 is operating at a feed rate-less than maximum, the liquid discharged by pump 5 is exhausted through Operation With motor 6. and pump 5 running and with cam roller its in engagement with cam I 01 so that control valve 85 is in the position shown in Figs. 1 and 2, the liquid discharged by pump 5 will flow through channel 99, valve casing 86, and channel 24 to reservoir I4 so that motor I2 is idle, piston 2 being held up by liquid trapped in the lower part of cylinder I by resistance valve 99.

As soon as motor 6 starts to drive pump 5, it also starts to drive shaft 60 of differential 35. At this time there is no pressure in cylinder I9 to cause the clutch to be engaged so that brake 84 holds shaftBZ stationary and the motion imparted to shaft 60 causes housing 50 to rotate and gear 59 to drive gear 10 which will rotate To start the transmission, the operator pulls valve stem ItI outward to the limit of its movement, thereby moving valve 95 to the position shown in Fig. 3 so that port 08 is open to port 09 and port 91 is open to passage 93. The liquid discharged by pump 5 will then flow through channel as, valve casing 85, and channel 95 to the upper end of cylinder I and cause piston 2 to advance and expel liquid from cylinder I through resistance valve 95, channel 97, valve casing 36, passage as in valve 05, port 81 and channel 24 to reservoir I4. Pump 5 is at this time delivering liquid at a predetermined maximum rate tocause piston 2 to advance at a predetermined rapid traverse speed and pump pressure is just sufficient to overcome the resistance of valve 99 and the inertia and friction of piston 2 and the parts connected thereto.

Piston 2 will advance crosshead 4 which will cause cable It to rotate cable drum l4 and thereby cause gear reducer I09 to rotate cam drum I08 and gear I3 to rotate gear I2. Since the clutch is not engaged atthis time, rotation of gear 72 has no effect upon differential 35. Just after drum I03 starts to rotate, it moves cam I I behind rollerIOt and then the operator may release stem HM as cam H0 will hold valve 05- in the position shown in Fig. 3.

Piston 2 will continue to advance at rapid traverse rate until camdrum I09, which rotates at a speed proportional to the speed of piston 2 as previously explained, has moved cam IIO beyond cam roller I06 and then spring I05 will shift valve 85 tdward the right into the position shown in Fig. 4 and roller I06 will engage cam III and hold the valve 85 in that position.

With valve 85in the position shown in Fig,

1o 4, port 88 will remain open to port 89 so that liquid'from pump 5 will continue to flow to the upper end of cylinder I and move piston 2 downward but port 90 will'be closed to passage 93 which will cause the following things to occur substantially simultaneously:

1. The liquid discharged from cylinder I into channel 91 can no longer flow freely to reservoir I4 but must flow from channel 91 through valve casing 88, channel 21. pressure reducing valve II, channel It, throttle 'I-3 and channel I5 into reservoir I4. Throttle |-8 will resist the flow of liquid therethrough but pump 5 will continue to deliver liquid to the upper end of cylinder I which will cause pump pressure to rise and piston 2 to create a back pressure in the lower end of cylinder I and in all channels connected thereto.

, cause piston 48 to move rod 41 and carriage 44 toward the left until carriage 44 engages adjusting screw 5|, thereby so adjusting transmission 36 that it will drive shaft BII-at the correct speed for fast feed operation of motor I2.

4. The lower end of lever 68 will move with. rod 41 and permit spring I 2 to'move throttle valve 'I to its fast feed position which may be varied by turning adjusting screw 5i.

5. The back pressure will extend through channel 27 to cylinder 19 and cause piston 18 to engage the clutch so that gear 10 will be driven by gear I2 and it will drive differential housing 50 at a speedproportional to the speed of piston 2.

6. Pump pressure will extend through channel I21 to cylinder I24 and cause piston I22 to reduce the displacement of pump 5 to the minimum determined by adjusting screw I28 at which displacement pump 5 will deliver at a rate sumcient to cause piston 2 to advance at the fast feed rate determined by the adjustment of throttle 'I.

Shifting valve 85 from the position shown in Fig. 3 to the position shown in Fig. 4 thus automatically causes the speed of motor I--2 to be changed from rapid traverse to a. desired fast feed rate, control transmission 35 to be adjusted so as to drive one leg of differential 55 at a speed proportional to the desired fast feed rate, a second leg of differential 35 to be driven at a speed proportional to the speed of motor I-2 and the volumetric delivery of pump 5 to be reduced to a minimum which is great enough to drive motor I2 at the desired fastfeed rate. If the speed of motor I2 should vary from the desired feed rate, the speed of differential housing 55 would vary relative to the speed of shaft 60 and cause shaft 62 to rotate and effect adjustment of throttle valve I to correct such variation in the speed of motor I- -2.

Motor I-2 will continue to operate at the fast feed rate and cam drum I08 will continue to rotate until it moves cam III beyond cam roller I06 and then spring I05 will vshift valve 05 to the position shown in Fig. 5 and cam roller I06 will engage cam I I2 and hold valve in that position. I

Shifting valve 85 from the position shown in Fig. 4 to the position shown in Fig. 5 blocks communication between port 92 and port 9| and opens port 92 to chamber 94 which destroys valve casingBG, passage 93, port 81 and channel 24 into reservoir I4.

Moving control rod 41 toward the right causes lever 68 to move throttle valve 1 toward the right to reduce the effective areas Of grooves II and thereby reduce the speed of motor I-Z to a desired slow feed rate as determined by the adjustment of screw 50. Moving carriage 44 toward the right causes control transmission 36 to reduce the speed of shaft 60 to the correct speed for the desired slow feed operation of motor I2 Shifting valve 85 from the position shown in Fig. 4 to the position shown in Fig. 5 makes no other change in the circuit. Pump 5 continues to deliver liquid to the upper end of cylinder I and the liquid discharged from the lower end of cylinder I continues to flow through throttle 1-8 which now reduces the speed of motor I2 so that the liquid discharged by pump 5 is in excess of motor requirements and the excess is exhausted through relief valve I29. The back pressure continues to hold the clutch engaged so that differential housing 56 continues to be driven at a speed proportional to the speed of motor I2 and, if the speed of motor I2 should vary from he desired feed rate, the speed of differential housing 56 would vary relative to the speed of shaft 60 and cause shaft 62 to rotate and effect adjustment of throttle valve 1 to correct such variation in speed as previously explained.

Motor I-2 will continue to operate at the slow feed rate and cam drum I08 will continue to rotate until it moves cam IIZ beyond cam roller I06 and then spring I05 will shift valve 85 toward the right to the limit of its movement as shown in Fig. 6.

With valve 85 in the position shown in Fig. 6, port 89 is open to port 90 so that the liquid discharged by pump 5 may flow through channel 96, valve casing 86, channel 91 and check valve 98 to the lower end of cylinder I and cause iston 2 to move upward and eject liquid from the upper end of cylinder I. Port 98 is open to port 81 so that the liquid ejected from cylinder I may flow through channel 95, valve casing 86 and channel 24 to reservoir I4. Port 9| is open to chamber 94 so that liquid may escape from cylinder 19 through channel 21, valve casing 86, passage 93 and channel 24 into reservoir I4 and thereby render gear I3 ineffective to drive differential housing 56.

Motor I2 is thus reversed which causes pump pressure to drop to a low value and permit spring I25 to increase the displacement of pump 5 to the predetermined maximum so that piston 2 is retracted at rapid traverse speed. As piston 2 retracts, torsion spring 15 will rotate gear I3 and drums I4 and I08 in a direction opposite to the direction in which they rotate during advance of piston 2. Drum I4 will wind cable 16 thereon and thereby maintain the speed and total angular movements of gear I3 and drums I4 and I08 proportional to the speed and total linear movement of piston 2. Gear 12 will be driven by gear I3 but it cannot drive gear I0 as the clutch is not engaged at this time.

Retraction of piston 2 and rotation of gear I3 and drums I4 and I08 will continue until cam I01 on drum I08 engages cam roller I06 and 12 shifts valve to the position shown in Figs. 1 and 2 to bypass pump 5 as previously explained. The transmission will then come to rest with its parts in the positions occupied before the above described cycle of operations was initiated.

The invention herein set forth is susceptible of various modifications and adaptations without departing from. the scope of the invention which is hereby claimed as follows:

1. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, means for supplyingv liquid to said motor to energize the same, a throttle for controlling the outflow from said motor to thereby control the speed of said motor, and means responsive to a variation in the speed of said motor relative to the speed of said element for adjusting said throttle to vary the resistance thereof and thereby correct said variation in motor speed.

2. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for controlling the speed of said motor, means responsive to a variation in the speed of said motor relative to the speed of said element for adjusting said throttle to vary the resistance thereof and thereby correct said variation in motor speed, and means responsive to said motor completing a given movement for adjusting said throttle to vary the resistance thereof and thereby vary the speed of said motor.

3. The combination with an element adapted to move at a plurality of predetermined speeds, of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for controlling the speed of said motor, means for automatically adjusting said throttle from one to another of a plurality of positions in each of .which it establishes a predetermined speed of said motor, means for changing the speed of said element from one to another of said predetermined speeds substantially simultaneously with the adjustment of said throttle, and means responsive to a variation in the speed of said motor relative to the speed of said element for further adjusting said throttle to thereby correct said variation in motor speed.

4. A hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said .motor to energize the same, a'relief valve for the discharge of liquid delivered by said pump in excess of motor requirements, a control for reducing the delivery of said pump to a predetermined minimum rate in response to pump pressure reaching a given maximum to thereby prevent an excessive volume of liquid from being discharged through said relief valve, a throttle for resisting the discharge of liquid from said motor, the resistance offered by said throttle causing said pump to create pressure which effects operation of said control, and a valve for bypassing the outflow from-said motor around said throttle to enable said pump to operate said motor at high speed.

5. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for resisting the flow of liquid through said motor, a control valve for controlling said motor and adapted in one position 1 adapted in another position to direct saidliquid through said throttle to enable said throttle to control the speed of saidfmotor, means responsive to said valve being shifted to the second mentioned position for adjusting said throttle to a predetermined position, and means responsive to a variation in the speed of said motor relative to the speed of said element for further adjusting said throttle to thereby correct said variation in motor speed.

6. A hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said motor to energize the same, a throttle for limiting the rate of discharge of liquid from said motor to thereby control the speed of said motor, a pressure reduction valve interposed between said throttle and said motor for reducing the pressure of the liquid delivered to said throttle to a substantially constant value, a relief valve for the discharge of liquid delivered by said pump in excess of motor requirements, a control for reducing the delivery of said pump to a predetermined minimum rate in response to pump pressure reaching a given maximum to thereby prevent an excessive volume of liquid from being discharged through said relief valve the resistance offered by said throttle causing said pump to create pressure to effect operation of said control, and means responsive to movement of said motor for adjusting said throttle to vary the rate of fiow therethrough and thereby vary the speed of said motor.

7. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor,

means for supplying liquid to said motor to enercontrolling said motor and adapted in one position to bypass the liquid around said throttle to enable'said motor to operate at high speed and adapted in another position to direct said liquid through said throttle to enable said throttle to control the speed of said motor, means responsive to said valve being shifted to the second mentioned position for adjusting said throttle to a predetermined position, means for shifting said valve, means responsive to movement created by said motor for operating said valve shifting means, and means responsive to a variation in the speed of said motor relative to the speed of said element for further adjusting said throttle to thereby correct said variation in motor speed.

8. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for controlling the speed of said motor, means for rendering said throttle efiective or ineffective to control said motor, a difierential having one leg driven from said element at a speed proportional to the speed thereof, a drive for driving the second leg of said differential from said motor at a speed proportionalto the speed thereof to thereby cause the third leg of said differential to operate in responseto a variation in the speed of said motor relative to the speed of said element, means responsive to operation of said third leg for adjusting said throttle to cause it to correct said variation in motor speed, said drive including a clutch for preventing said drive from driving said difierential when said throttle is ineffective to control said motor, and means for l4 causing said clutchto be engaged only time said throttle is effective v 9. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comp'risinga hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for controlling the speed of said motor, means for rendering said throttle efiective or ineffective to control said motor, a differential having one leg driven from said element at a speed proportional to the speed thereof,

a drive for driving the second leg of said difierential from saidmotor at a speed proportional to the speed thereof to thereby cause the third leg of said differential to operate in response to a variation in the speed of said motor relative to the speed of said element, means responsive to operation of said third leg for adjusting. saidwhen said throttle is ineffective to control said motor, means for causing said clutch to be engaged only during the time said throttle is effective, and a brake for preventing operation of the third leg of said differential during disengagement of said clutch.

10. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for controlling the speed of said motor, means for rendering said throttle efiecti've or inefiective to control said motor, a differential having one leg driven ,from said element at a speed proportional to the speed thereof, a drive for driving the second leg of said dilTerential from said motor at a speed proportional to the speed thereof to thereby cause the third leg of said differential to operate in response to a variation in the speed of said motor relative to the speed of said element, means responsive to operation of said third leg for adjusting said throttle to cause it to correct said Variation in motor speed, means for varying the speed of the first leg of said differential relative to the speed of said element, and means responsive to said throttle-being rendered efiective .for simultaneously adjusting said throttle and said speed varying means.

11. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for controlling the speed of said motor, means for rendering said throttle efiective or ineffective to control said motor, a

differential having one leg driven from said element at a speed proportional to the speed thereof, a drive for driving the second leg of said difierential from said motor at a speed proportional to the speed thereof to thereby cause the third leg of said differential to operate in response to a variation in the speed of said motor relative to the speed of said element, means responsive to operation of said third leg for adjusting said throttle to cause it to correct said variation in motor speed, means for varying the speed of the first leg of said differential relative to the speed of said element, means responsive to said throttle being rendered efiective for adjusting said throttle to a position to cause said motor to operate at one controlled speed and for simultaneously adjusting said speed varying means, and means responsive to said motor completing a given moveduring. the

ment for adjusting said throttle to a difierent position to cause said motor to operate at another controlled speed and for simultaneously adjusting said speed varying means.

12. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for resisting the discharge of liquid from said motor to thereby con trol the speed of said motor, a pressure reduction valve interposed between. said throttle and said motor for reducing the pressure of the liquid delivered to said throttle to a substantially constant value, and means responsive to a variation in the speed of said motor relative to the speed of said element for adjusting said throttle to vary the resistance thereof and thereby correct said variation in motor speed.

13. The combination with an element adapted to move at a plurality of'predetermined speeds,

of a hydraulic transmission comprising a hydraulic motor, means for supplying liquid to said motor to energize the same, a throttle for resisting the discharge of liquid from said motor to thereby control the speed of said motor, a pressure reduction valve interposed between said throttle and said motor for reducing the pressure of the liquid delivered to said throttle to a substantially constant value, means for automatically adju;ting'- said throttle from one to another of a plurality of positions in each of which it establishes a predetermined speed of said motor, -means for changing the speed of said element from one to another of said predetermined speeds substantially simultaneously with the adjustment of said throttle, and means responsive to a variation in the speed of said motor relative to the speed of said element for further adjusting said throttle to thereby correct said variation in motor speed.

14. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said motor to energize the same, a throttle for resisting the flow of liquid through said motor, means responsiveto a variation in the speed of said motor relative to the speed of said element for adjusting said throttle to vary the resistance thereof and thereby correct said variation in motor speed, and a control responsive to pump pressure reaching a given maximum for reducing the delivery of said pump substantially to the rate required to operate said motor at the speed determined by said throttle.

15. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said motor to energize the same, a throttle for resisting the flow of liquid through said motor, means responsive to a variation in the speed of said motor relative to the speed of said element for adjusting said throttle to vary the resistance thereof and thereby correct said variation in motor speed, a control 16 gize the same, a throttle for resisting the discharge of liquid from said motor, means responsive to a variation in the speed of said motor relative to the speed of said element for adjusting said throttle to vary the resistance thereof and thereby correct said variation in motor speed, a control responsive .to pump pressure reaching a given maximum for reducing the delivery of said pump substantially to the rate required to operate said motor at the speed determined by said throttle, a valve for bypassing the outflow from said motor around said throttleto enable said pump to operate said motor at high speed, and

means responsive to said motor completing a given movement for shifting said valve.

17. The combination with an element adapted to move at a predetermined speed, of a hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said motor to energize the same, a throttle for resisting the flow of liquid through said motor, means responsive to a variation in the speed of said motor relative to the speed of said element for adjusting said throttle to vary the resistance thereof and thereb correct said variation in motor speed, a control responsive to pump pressure reaching a given maximum for reducing the delivery of said pump substantially to the rate required to operate said motor at the speed determined by said thrott e, and means responsive to said motor completing a given movement for adjusting said throttle to var the resistance thereof and thereby vary the speed of said motor.

18. A hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said motor to energize the same, a throttle for resisting the discharge of liquid from said motor, a relief valve for the discharge of liquid delivered by said pump in excess of motor requirements, and a control for reducing the delivery of said pump to a predetermined minimum rate in response to pump pressure reaching a given maximum to thereby prevent an excessive volume of liquid from being discharged through said relief valve.

1 A hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said motor to energize the same, a throttle for resisting the discharge of liquid from said motor, a relief valve for the discharge of liquid deivered by said pump in excess of motor requirements, a control for reducing the delivery of said pump to a predetermined minimum rate in response to pump pressure reaching a given maximum to thereby prevent an excessive volume of liquid from being discharged through said relief valve, and means responsive to said motor completing a given movement for adjusting said throttle to vary the resistance thereof and thereby vary the speed of said motor.

20. A hydraulic transmission comprising a hydraulic motor, a pump for supplying liquid to said motor to energize the same, a throttle for resisting the discharge of liquid from said motor,

"'a pressure reduction valve interposed between said throttle and said motor for reducing the pressure of the liquid delivered to said throttle to a substantially constant value, a relief valve for the discharge of liquid delivered by said pump in excess of motor requirements, a control for reducing the delivery of said pump to a predetermined minimum rate in response to pump pressure reaching a given maximum to thereby prevent an excessive volume of liquid from being discharged through said relief valve, a valve adapted pump to create a pressure which will enable said control to reduce the rate of pump delivery.

WALTER. FERRIS.

REFERENCES CITED The following references are of record in the file of this patent:

Number 18 UNITED STATES PATENTS Name Date Ferris Dec. 31, 1929 Vickers -1 Dec. 4, 1934 Ferris Feb. 2, 1936 Douglas May 18, 1937 Groene et al. Feb. 21, 1939 Ferris Aug. 13, 1940 Herman et a1 Feb. 24, 1942 Vickers July 28. 1942 Montelius Oct. 5, 1943 

